Aaron and Stearns list several contributing items to the US's abysmal ranking:
• media consolidationThe complete report (PDF) is pretty hefty, at least if you're on dialup, like me. There is an article available online giving the highlights. Several other interesting articles are available, too.
• the Pentagon's covert propaganda campaign using retired military officers
• the campaign by phone and cable companies "to dismantle the long-standing principle of Net Neutrality"
• Aaron claims that "nearly 100 journalists were arrested and detained in St. Paul, Minn., while trying to report on the Republican National Convention." (He doesn't say where he got this figure from, though. The highest I've seen to date other than this is 46.) However, it is clearly true that the treatment of protestors and journalists (not to mention medics!) at the RNC was appalling, unconstitutional, and beyond the pale.
The first list was published in 2002, and the US was at 17th place at that point. In 2006, we'd sunk to 53. So I suppose this is the sign of an upward trend, which is heartening, but somehow I can't feel jubilant about 36th place.